The embodiments described herein relate generally to an override device for a circuit breaker, and more particularly, to methods and systems used to activate and de-activate over-current protection in the circuit breaker.
A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overloaded or shorted circuits. A coupler mechanism of the circuit breaker can be actuated to open and close contacts to which a load is connected. Circuit breakers have an over-current trip unit that provides over-current protection. Conventional over-current trip units use a magnetic yoke that surrounds a current-carrying leader. The magnetic yoke has an anchor that is movable along an axis and a spring that applies a resistive force against movement of the anchor. Current flowing through the leader induces a magnetic force that causes the anchor to apply a force against the resistance of the spring. If the current flowing through the leader exceeds a pre-determined value, the magnetic force acting on the anchor is greater than the force of the spring. Thus, the anchor is pulled toward the magnet which actuates a coupler to interrupt or “trip” the circuit. Some applications may require an override of the over-current trip unit. In these situations, an override device is required to permit current flow through the circuit breaker when the current exceeds the pre-determined value.